exedra vs penetralia

exedra

noun
  • A semicircular recess, with stone benches, used as a place for discussion. 

  • A curved bench with a high back. 

penetralia

noun
  • The innermost parts of a building, such as a shrine, recess or a sanctuary within a temple. 

  • The innermost, secret or hidden parts; mysteries. 

How often have the words exedra and penetralia occurred in a corpus of books? (source: Google Ngram Viewer )